Esters and mixtures thereof with organotin compounds

ABSTRACT

wherein x and y are 1-6, R4 and R9 are alkyl, alkenyl, cycloalkyl or optionally substituted aromatic aralkyl or aralkenyl hydrocarbyl group, R3 and R5 are as R4 or R9 or is hydrogen or R3 and R5 form a cycloalkyl ring. The organotin stabilisers are carboxylates, mercapto carboxylates, carboxylate ester from diacids, sulphides, mercaptides or thiostannoic acids. An ester, which is costabiliser of mono or di-organotin stabilisers for halogen containing resins, is of formula

United States Patent 1191 Coates et al. Dec. 9, 1975 [54] 1351113115 AND M TU E F W 3,764,571 10/1973 Jennings 252/400 R ORGANOTIN COMPOUNDS 3,845,017 lO/l974 Collins 260/4575 K [75] Inventors: Harold Coates, Womboume; John pn-mary Examin, Bem-amn R Padgett i f t' Assistant Examiner-Donald P. Walsh lfl'khar Attorney, Agent, or Firm-Robert P. Auber; Kenneth Edgbaston, of England G. Wheeless; Robert Spector [73] Assignee: Albright & Wilson Limited, Oldbury near Birmingham, England ABSTRACT An ester, which is costabiliser of mono or di-organotin [22] Flled' 1974 stabilisers for halogen containing resins, is of formula [2|] Appl. No.: 442,874

{30] Foreign Application Priority Data HOOCR Feb. l9, i973 United Kingdom............... 07984/73 EH0}! [52] US. Cl 252/400 R; 252/406; 260/45.75 K 51 Int. c1. C09K 15/32; c091 15/10; C08K 00/00 [58] Field of Search 252/400 R, 406, 45.75 K, R'OOCQHFS 252/399 wherein x and y are l-6, R and R are alkyl, alkenyl, cycloalkyl or optionally substituted aromatic aralkyl [56] References Cited or aralke nyl hydrocarbyl group, R and R are as R or UNTFED STATES PATENTS R or is hydrogen or R and R form a cycloalkyl ring. 3,398,1l4 8/l968 Pollock........................... 252/400 R The organgtin gtabilisers are carboxylates, mercapto 31433-159 12/1969 Kauder 252/400 R carboxylates, carboxylate ester from diacids, sul- 3,627,7l6 l2/l97l Cohen 252/400 R phides mercaptides or thiostannoic acids 3,642,677 2/l972 Brecker 252/400 R 3,647,748 3/1972 Brook 252/400 R 10 Claims, N0 Drawings 3,715,333 2/1973 Larkin 252/400 R ESTERS AND MIXTURES THEREOF WITH ORGANOTIN COMPOUNDS The present invention relates to compounds, which act as costabilizers for organotin compounds in the stabilization of Halogen containing polymers such as polyvinyl chloride.

ln the complete specification of our Copending British application Ser. No. 5504/72 we have described organotin compounds of the general formula HOH cinoocc, n s R,

R, R, c

HOH

inoociz,

wherein a is or 1, each of x, .r', y and y, which are the same or different, is an integer of l 6 each of R R R and R,, which are the same or different is an alkyl group of l to 12 carbon atoms, a cycloalkyl group, an aromatic hydrocarbyl group or an aralkyl hydrocarbyl group, each of R and R which are the same or different, is as defined above for R R R and R or is an alkyl group of 13 21 carbon atoms, an alkenyl group of 2 to 21 or an inertly substituted aromatic hydrocarbon group, each of R R R and R which are the same or different, is as defined above for R and R or is hydrogen or at least one of the pairs R and R and R and R together with the carbon atom to which they are attached, forms a cycloalkyl ring, and X is oxygen or sulphur. These compounds are stabilizers for halogen containing resins.

We have found that ester derivatives of the tin free part of the above stabilizers can act as costabilizers for organotin compounds.

The present invention provides esters of the general formula CHZOOCR,

CHOH

C'H,OOC,,H S R,

C R 00: C,H2,-S n

wherein, each of R and R which are the same or different, is an alkyl group of 1 to 21 carbon atoms, an alkenyl group of 2-2l atoms, cycloalkyl group, aromatic hydrocarbyl group e.g. of 6 to 19 carbon atoms e.g. phenyl or aralkyl or aralkenyl hydrocarbyl group e.g. of 7 to 19 carbon atoms such as benzyl, orstyryl or an inertly substituted derivative of the aromatic, aralkyl or aralkenyl hydrocarbyl group, wherein the substituent is preferably at least one group of formula -COOR., -OOCR or SSR., each of R3 and R5. which are the same or different, is as defined above for R and R or is hydrogen or R and R together with the carbon atom to which they are attached forms a cyclo alkyl ring, preferably a cyclohexane ring, and each of x and y which are the same or different, is an integer of I 6.

R is preferably an alkyl group of 4 18 carbon atoms e.g. (F12 carbon atoms such as an iso-n-octyl group, or cycloalkyl group of 5 8 carbon atoms e.g. cyclohexyl group. R is preferably hydrogen of alkyl of l to 6 carbon atoms e.g. a methyl group. R is preferably an alkyl or alkenyl group of 10 to 19 carbon atoms, preferably a linear one e.g. of formula CH (CH where z is an integer of 9-18, preferably 10-17 and especially 16. R is preferably a phenyl, styryl or substituted phenyl (the substituents being for example alkyl of 1 to 6 carbon atoms especially methyl, or alkoxy of l to 6 carbon atoms, especially methoxy or hydroxy) group, branched chain alkyl group of 3 10, eg 4 8 carbon atoms, preferably that in which the free valency is at the point of branching i.e. of formula -CH R R where R and R are alkyl groups of 1 to 6 carbon atoms, especially ethyl and butyl, e.g. pent 3 yl and hept 3 yl groups or a straight chain alkyl group of 7 to 13 carbon atoms e.g. n-nonyl and n-undecyl group .r and y are preferably 1 or 2. The groups C ll and C l-l and preferably linear e.g. of formula (CH In preferred compounds, the group represents groups of formula Preferred compounds are those of formula wherein each of R and R which are the same or different, is an alkyl group of 1 to 12 carbon atoms, a cycloalkyl group, an aryl or aralkyl group, R is hydrogen, an alkyl or aryl group, R is an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group or an aryl or aralkyl group, z is an integer of l to 20 and x and y are integers of l to 6. Preferably R is a methyl group, R is hydrogen or alkyl e.g. methyl group, R is a phenyl or styryl group, a substituted phenyl group, a branched chain alkyl group of 4 8 carbon atoms or a straight chain alkyl group of 7 to 13 carbon atoms, R is an alkyl or cycloalkyl group of 4 to 8 carbon atoms, 1: and y are l or 2 and z is 10-16.

The present invention also provides a process for preparing the ester compounds, which comprises reacting substantially equimolar amounts of a glycerol ester of formula R COOCH: OOCC,,H ,,SH with a carbonyl compound of formula R R CO and a mercapto ester of formula R OOCC H SH. Alternatively, an acid of formula iIMOOCR.

HOH

can be reacted by known methods with a hydroxylic compound of formula R OH or a halide of formula R Hal (when R, is an alkyl cycloalkyl or aralkyl group and Hal is chlorine, bromine or iodine), the reaction with the hydroxylic compound being preferably carried out in the presence of an acid catalyst, and the reaction with the halide being preferably carried out in the presence of a basic catalyst. The acid is preferably prepared by reacting substantially equimolar amounts of the glycerol ester with the carbonyl compound and a mercapto acid of formula HOOC H SH. Thus the ester compounds can be prepared by reacting substantially equimolar amounts of the glycerol ester with the carbonyl compound and a mercapto compound of formula R OOCCJ-l Sl-l, where R is R or hydrogen, and where R is hydrogen, reacting the product with the hydroxylic compound or halide.

Preferably the glycerol ester is prepared in situ by reaction of substantially equimolar amounts of a compound of formula R COOCH,CHOHCH,OH and a mercapto acid of formula HOOC C,,H,,,sH. The terms substantially equimolar amounts" means here not more than 30% molar excess of any reactant. The term known methods means methods heretofore used or described in the chemical literature.

Thus the compounds of the invention are generally prepared by the reaction of mono-ester of glycerol, such as glycerol mono-stearate, with a mercapto carboxylic acid such as thioglycollic acid or ,B-mercaptopropionic acid and subsequently admixing this with an aldehyde or ketone such as 2 ethyl butyraldehyde, dodecylaldehyde, anisaldehyde, cinnamaldehyde or methyl nonyl ketone, and a mercapto-carboxylic ester such as iso-octyl thioglycollate or iso-octyl B- mercaptopropionate.

Frequently the reactions to fonn the ester compounds of the invention are carried out in the same solvent medium, which may be an aromatic hydrocarbon, e.g. benzene, toluene or xylene, an aliphatic hydrocarbon e.g. hexane or petroleum ether b.p. or a cycloaliphatic hydrocarbon e. g. cyclohexane). It is often desirable (except in the reaction of the halide) to have an acidic catalyst present in the reaction, e.g. p-toluene sulphonic acid, hydrochloric acid or a metal chloride suitable as a Friedel Crafts catalyst, such as zinc chloride.

The esters of the invention are costabilizers with organotin compounds for halogen containing resins. The present invention also provides stabilizer compositions comprising an ester of the invention and an organotin compound of formula wherein R represents an alkyl group of 1-12 carbon atoms, preferably 4-8 carbon atoms, e.g. butyl or octyl, a cycloalkyl group preferably of 5-8 carbon atoms, e.g. a cyclohexyl group, an aromatic hydrocarbyl group e. g. of 6-19 carbon atoms e.g. phenyl or aralkyl hydrocarbyl group e.g. of 7-19 carbon atoms such as benzyl, R is as defined for R or each of R R and R which are the same or different is of formula OOCR OOCR COOR SC ,,l-I, COOR, or -SR,, or R and R together represent -S, 0OCR COO-, SC,H,,COO- or R and R together represent S and R represents -SH, wherein R is w defined above, preferably an alkyl group of 8-18 carbon atoms, especially 11 or 12 carbon atoms, x is as defined above, and is preferably 1 or 2, and R is an alkylene group e.g. of 1 to 10 carbon atoms, an alkenylene group e.g. of 2 to 10 carbon atoms a cycloalkylene group e.g. of 5 to 7 carbon atoms such as cyclohexylene or an arylene group, preferably a divalent aromatic hydrocarbyl group e.g. of 6 to 18 carbon atoms such as phenylene,

For example the organotin compound may be a mono or di organotin carboxylate of formula R, (R Sn(OOCR,), where R represents R, or OOCR e.g. dibutylin dilaurate or dioctyltin dilaurate. The organotin compound may be a mono or di organo carboxylate from a dicarboxylic acid or a half ester thereof, i.e. of formula R, (R ,)Sn(O0CR COOR,), where R represents R, or OOCR COOR or (R,),Sn(OOCR,. -,COO) e.g. where R is an alkylene group of 1 to 6 carbon atoms e.g. 1,2 ethylene or an alkenylene group of 2-6 carbon atoms, preferably CH CH- and where R, is e. g. an iso octyl group; examples of these carboxylates are di butyltin and di octyltin maleates, and dibutyltin and di octyltin bis (iso octylmaleate), and the corresponding mono alkyltin tris compounds. The organotin compound may be a sulphide, a mercaptide or thio stannoic acid or thio stannoic acid ester, of formula R,Sn (=8) SH, R,Sn (=8) SR R (R Sn (SR (R,),SnS where R represents R or SR.., and R preferably represents an alkyl group of 8-18 carbon atoms e.g. of 12 carbon atoms; examples of such compounds are dibutyltin sulphide and bis (lauryl mercaptide), di octyltin sulphide and bis (lauryl mercaptide) and butyltin and octyltin thio stannoic acids and lauryl esters thereof.

Preferably the organotin compounds are mercapto carboxylate esters of formula R, (R Sn (S (Cl-l COOR,,) wherein R represents R or S (CH ),COOR or cyclic esters of formula (R,) Sn (S(CH ),COO), wherein x is l or 2 and R is an alkyl group of 6 to 18, preferably 6-l 2 carbon atoms, especially an iso octyl group; examples of such compounds are di butyltin and di octyltin bis (iso octyl thio glycollates), and dibutyltin and di octyltin bis (iso octyl B-mercaptopropionates), and the corresponding mono alkyltin tris mercaptocarboxylates, and butyl and octyltin cyclic thioglycollates and B-mercaptopropionates.

The esters of the invention and organotin compounds are preferably present in the stabilizer compositions in a weight ratio of 0.1 1 to 1.5 1, preferably 0.2 l to l I, especially 0,3 l to 0.8 l.

The present invention also provides polymeric materials comprising a halogen containing resin and, as stabilizer therefor a stabilizer composition of the invention, usually in an amount of 0.] to by weight, preferably 1 to 8%, especially 1.1 to 6% (based on the weight of the resin). Typically the material contains l-3% by weight of organotin compound and 0.1 3% by weight of ester (based on the weight of the resin).

The resin normally contains at least 40% by weight of chlorine. Usually it will be a polymer or co-polymer of vinyl chloride or vinylidene chloride but posthalogenated polyvinyl chloride or post-halogenated polyolefins, such as polyethylene, e.g. post chlorinated compounds, may be employed if desired. Suitable monomers which may form such copolymers with vinyl chloride and vinylidene chloride include for example acrylonitrile, vinyl acetate, methyl methacrylate, diesters of fumaric acid and maleic acid, ethylene, propylene and lauryl vinyl ether and these co-monomers may be present in an amount of up to 25% of the total weight of monomers co-polymerised.

Optionally, but advantageously, compositions according to the invention also contain hindered phenols, that is those having at least one alkyl substituent in a position ortho to the hydroxyl group, as auxiliary stabilizers. Such phenols preferably have l-8 carbon atoms in each alkyl group, which is especially a tertiary butyl group. Examples of such phenols include butylated hydroxy-anisols, 2,6-di-tert.-butylphenol, methylene bis- (2,4-di-tert.-butylphenol), methylene bis-( 2,6-di-tert- .butylphenol), methylene bis-(2,6di-tert.-butyl-3- metlrylphenol), 4,4'-butylidene bis-(ti-terL-butyl-3- methylphenol), methylene bis-(4-ethyl-6-tert.-butylphenol), methylene bis-(4-methyl-2,6-di-tert.-butylphenol). Particularly preferred, however, is 2,6-ditert.-butyl-4-methyl-phenol.

Such phenols may be present in an amount of up to 3% preferably from 0.0] to 0.05% by weight of the resin and will normally be present at about 4-10% by weight, preferably 5 8% based on the total amount of organotin compounds used. Esters of phosphorus and thiophosphorous acid may be employed in compositions according to the invention. Such compounds in clude halophosphites such as tris chloropropyl phosphite and polymeric phosphites such as those from hydrogenated 44'-isopropylidene diphenol. Preferred phosphites and thiophosphites, however, are monomers having no substituents in the organo-group and having no more than one sulphur atom. These include triaryl phosphites and trialkyl phosphites. Such compounds include, for example, triphenyl phosphite,

trixylyl phosphite, trinonyl phenyl phosphite and trioctyl phosphite. Diesters of phosphorous acid such as di- 5 isopropyl phosphite, dibutyl phosphite and diphenyl phosphite are also of use. Particularly preferred, however, are the mixed alkyl aryl phosphites such as octyl diphenyl phosphite, isodecyl diphenyl phosphite and di-isodecyl phenyl phosphite. This particularly pronounced effect may also be obtained by employing a mixture of a triaryl phosphite and an alcohol in conjunction with the organotin compound. A particularly suitable mixture is that of triphenyl phosphite and isodecanol.

The stabilizer composition of the invention can also contain an epoxy compound, as may be desired for example in cases where a delay of initial colour change of the polymer is desired. Epoxy compounds which may be employed in such compositions include butyl epoxy stearate, esters of epoxidised oleic acid and compounds of the formula CH CH The stabilizer compositions as described above, optionally including a hindered phenol, an alkyl aryl phosphite or aryl phosphite or an epoxide, will often be used as the only stabilizer in a polymeric vinyl chloride or vinylidene chloride composition. However, if desired conventional thermal stabilizers may also be included. These may include, for example, metal soap stabilizers, such as cadmium, barium, or zinc salts of fatty acids, or lead salts such as lead carbonate or stearate or dibasic lead phosphite or phthalate, or tribasic lead sulphate.

In the practice of the invention the stabilizer composition may be mixed with the resin in the conventional manner for example by milling with the resin on heated rolls at IOU-160C e.g. about 150C, although higher temperatures may be used when convenient, or by being mixed with particles of the polymer and then melting and extruding the mixture or by adding the stabilizer to a liquid resin.

The organotin stabilizer formulation may be employed in either plasticized resin compositions, for example those plasticized with carboxylic ester plasticizers e.g. di-Z-ethylhexyl phthalate, dibutyl sebacate or diiso octyl phthalate or with phosphate esters such as tri(alkyl phenyl) phosphates or may be employed in rigid compositions. Such rigid compositions contain little or no plasticizers although for some applications up to about 10% by weight of plasticizer may be present. This is in contrast with plasticized compositions where the amount of plasticizers present is normally greater than 50% by weight of the polymeric material and is often greater than 100% on that basis; amounts of 30 150% are often used.

In addition to the stabilizers, the compositions of the invention may also contain conventional additives, e.g. pigments, fillers, dyes and ultraviolet absorbing agents.

The invention is illustrated in the following Examples:

EXAMPLE 1 a( !)ll 1 z HOC CH,CH, SCH,CH,COOCH,

CH CH,

Glycerol mono stearate (34.8g, 0. l M) and B mercaptopropionic acid (10.6g, 0.1M) were refluxed in toluene (250 ml) in the presence of p-toluene sulphonic acid (0.2g) till the calculated amount of water had collected (to give c n coocn --CH(OH)CH OOC CH Cl-bSl-l).

2 ethyl butyraldehyde (l0.0g, 0.1M) and iso octyl B-mercaptopropionate (21 .8g, ().lM) were also added into the above warm solution and the mixture refluxed until the calculated amount of water had collected again. The hot solution was then rapidly filtered under partial vacuum and finally the toluene was removed from the warm solution under reduced pressure.

The product is a white soft waxy solid at room temperature.

Analysis Calculated Found S= 8.57% S=8.6% H l0.4% H 1.43%

its structure was also confirmed by IR. and N.M.R. analysis.

EXAMPLE 2 CH,(CH,] COOCH,

noc c H 0 scmcn coodn.

\ scmcmcoocm This compound was prepared by the same method as in Example I using the following quantities:

The product is a slightly yellow soft waxy solid at room temperature. lts structure was confirmed by IR. and N.M.R. analysis.

EXAMPLE 3 H, OOC (CHAN CH, EHOH H,OOC CH,S

CH(CH=)| CH This compound was prepared by the same method as in Example 1 using the following quantities:

Step (1) The product is white soft waxy solid at room temperature.

Calculated Found S 7.2 S 7.7 H 10.0% H= 10.8%

its structure was confirmed by IR. and N.M.R. analysis.

EXAMPLE 4 Salicylaldehyde (102g, 0.1M), iso-octyl thioglycollate (20.4g, 0.1M) and thioglycollic acid (9.2g, 0.1M) were refluxed in toluene (250ml) in the presence of ptoluene sulphonic acid (0.2g) till the calculated amount of water had collected (to give OH o sc incoon Analysis Calculated Found 8% 8.6 S% 8.1 H% =9.2 H%= 9.73 C% 64.9 Carbon% 65.9

EXAMPLE 5 The tin free compounds of Examples l-4 of the present invention were tested as costabilizers with known organotin stabilizers for initial colour development of polyvinyl chloride on heating in comparison with the same organotin stabilizers without the tin free compounds.

3003 samples of Rigid PVC compositions are made up as follows:

(a) Polyvinyl chloride sold under the trade name Corvic D55/09 (b) Lubricant mixture of cetyl alcohol and stearyl alcohol sold under the trade name Plastilube 30 100 parts if marked in following Table 0.5 parts present cycloalkyl ring, and (2) an organotin compound of the formula wherein R, is selected from the group consisting of alkyl groups of 1 to 12 carbon atoms, cycloalkyl groups, aromatic hydrocarbyl groups or aralkyl hydrocarbyl groups, R is as defined for R or each of R TABLE Example Tin Free Compound Stabiliser Colour on Gardner Scale of Parts by wt. Parts by wt. after heating at 190C Example per 100 parts Name per 100 parts for given time in mins.

No. of Polymer of Polymer 0 3 5 7% 9 10 12% Comparative NIL x 1.33 O 1-2 4-5 6 l 0.26 x 1.33 0 0 l-2 7 l 0.53 x 1.33 0 0 l-2 8 l 0.80 x 1.33 0 0 l-2 10 l 1.33 x 1.33 0 0 1+ Comparative NIL y 1.33* 2 3 6 6 7 l l l 0.53 y 1.33 0 0 l 2 3 l3 1 1.00 y 1.33 0 0 1 2 3 Comparative NlL x 1.33 O 0 3 4-5 l4 2 0.53 x 1.33 O O 0 3 Comparative NlL y 1.33" 3 3 4-5 l5 2 0.53 y 1.33 0 l 2 Comparative NIL x 1,33" 0 2-3 3-4 16 3 0.53 x 1.33 0 0 3 Comparative NIL y 1.33* 3 3-4 4 17 3 0.53 y 1.33 0 1 3-4 Comparative NIL x 1.5" 0 0 2 4 18 4 0.6 x 1.5 0 0 0-1 2 Comparative NIL y l .5 2 2 3+ 4-5 l9 4 0.6 y 1.5 0 0 1- 2- We cla mt R and R which are the same or different, is selected 1. A stabilizer composition comprising l an ester of the general formula CH,OOC R,

HOH

pooc s 5 wherein each of x and y, which are the same or different, is an integer of 1 6, each of R and R which are the same or different, is selected from the group consisting of alkyl groups of l to 21 carbon atoms, alkenyl groups of 2 21 carbon atoms, cycloalkyl groups, aromatic hydrocarbyl groups, aralkyl hydrocarbyl groups and aralkenyl hydrocarbyl groups, each of R and R which are the same or different, is as defined above for R and R or is hydrogen or R and R together with the carbon atom to which they are attached, forms a from the group consisting of groups of formula OOCR.,, OOCR COOR --SC, .l-1, ,COOR and --SR,,, or R and R together is selected from the group consisting of groups of formula S, OOCR COO, and SC,H ,COO, or R and R together represent Sand R represents SH, wherein R R and x are as defined in claim 1 and R represents a group selected from the group consisting of alkylene, alkenylene, cycloalkylene and arylene groups.

2. A composition according to claim 1 wherein R represents an alkyl group of 4 8 carbon atoms.

3. A composition according to claim 1 wherever R is as defined for R in claim 21.

4. A composition according to claim 1 wherein R is as defined for R or each of R R and R is of formula OOCR where R, is an alkyl group of 8 18 carbon atoms.

5. A composition according to claim 1 wlifilbin R 4 is as defined for R or each of R R and R.@ l Bf rmula OOCR COOR or R and R togetli' SE of formula OOCR, COO, where R is an lawless 1 1 group of l 6 carbon atoms or an alkenylene group of 2 6 carbon atoms.

6. A composition according to claim wherein R and R are butyl or octyl groups, R is a group of formula -CH=CH and in the group of formula OOCR,. ,COOR R is an iso octyl group.

7. A composition according to claim 5 wherein R is as defined for R or each of R R and R is of formula SR or R and R together represent S-, or R and R together represent S- and R represents -SH, wherein R is an alkyl group of 8 18 carbon atoms.

8. A composition according to claim 1 wherein R is as defined for R or each of R R and R is of formula S (Cl-I COOR or R and R are together of formula S(CH ),COO-, where x is l or 2 and R is an alkyl group of 6 18 carbon atoms.

9. A composition according to claim 8 wherein the organotin compound is selected from the group consisting of dibutyltin and dioctyltin bis (iso octylthioglycollate), and dibutyltin and di octyltin, bis (iso octyl B-mercaptopropionate).

10. A composition according to claim 1 wherein the ester and organotin compound are in a weight ratio of 0.1 1 to 1.5 l. 

1. A STABILIZER COMPOSITION COMPRISING (1) AN ESTER OF THE GENERAL FORMULA
 2. A composition according to claim 1 wherein R1 represents an alkyl group of 4 - 8 carbon atoms.
 3. A composition according to claim 1 wherever R14 is as defined for R1 in claim
 21. 4. A composition according to claim 1 wherein R14 is as defined for R1 or each of R14, R15 and R16 is of formula -OOCR4, where R4 is an alkyl group of 8 - 18 carbon atoms.
 5. A composition according to claim 1 wherein R14 is as defined for R1 or each of R14, R15 and R16 is of formula -OOCR17COOR9 or R15 and R16 together are of formula -OOCR17COO-, where R17 is an alkylene group of 1 - 6 carbon atoms or an alkenylene group of 2 - 6 carbon atoms.
 6. A composition according to claim 5 wherEin R14 and R1 are butyl or octyl groups, R17 is a group of formula -CH CH- and in the group of formula OOCR17COOR9, R9 is an iso octyl group.
 7. A composition according to claim 5 wherein R14 is as defined for R1 or each of R14, R15 and R16 is of formula SR4, or R15 and R16 together represent -S-, or R15 and R16 together represent -S-and R14 represents -SH, wherein R4 is an alkyl group of 8 - 18 carbon atoms.
 8. A composition according to claim 1 wherein R14 is as defined for R1 or each of R14, R15 and R16 is of formula -S (CH2)x COOR9 or R15 and R16 are together of formula -S(CH2)xCOO-, where x is 1 or 2 and R9 is an alkyl group of 6 - 18 carbon atoms.
 9. A composition according to claim 8 wherein the organotin compound is selected from the group consisting of dibutyltin -and dioctyltin - bis (iso octylthioglycollate), and dibutyltin -and di octyltin, bis (iso octyl Beta -mercaptopropionate).
 10. A composition according to claim 1 wherein the ester and organotin compound are in a weight ratio of 0.1 : 1 to 1.5 :
 1. 